Buying ER collets

I've been thinking about buying larger er collets ER40 in particular. I am aware that they need a certain length inside them that will be longer than a conventional type in order to meet their spec.

The spec is proving to be the problem or lack of it. DIN blah blah is often mentioned great they all have the same shape. Looking at the lower cost options a run out spec is given in many countries but seldom in the UK unless they are being sold from the far east. Some even say well what you get might not look like the photo. It's even possible to pay hundreds of quid for a set that doesn't mention any spec. The Vertex spec's on their site look worse than some but the do appear to be measuring them some distance from the end of the collet as they should. That makes me wonder if some are just measuring the run out of the start of the bore.

Anyone found an answer to the problem?

John

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I've never used ER Collets, and maybe never will, but

This looks like an honest description of a decent product

... I offer it only as a 'baseline' reference.

MichaelG.

Yes, Richard Gordon in MEW 232.

Neil

Here is one of the few examples of the way that collets should be spec'd that is also meaningful.

**LINK**

They will also assume engagement along the full length of the collet's socket. Bit of a difference isn't there even with best precision.

Sorry Neil that answer is no good to me - I suppose I could lap them as I use them. Or do what ever that article suggests.

John

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I purchased a full set from here **LINK** work fine for me be it lathe or milling machine even with duty etc not a bad price, OK took a couple of weeks to appear.

Bob

Information on er collets and other stuff is available on the WNT tooling centre website. (Milling- rotating tools- collet chucks). Centro P chucks with precision collets have a stated run out of .0001mm. I use these chucks professionally. Roy M.

Oops! Runout is .001mm Roy M.

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Sorry, John ... I'm struggling to understand that rhetorical question.

Bit of a difference between what and what ?

MichaelG.

I buy er 40 collets from arc as and when I need them,rather than buying a set and not using half of them..

I've mainly only used them for holding milling tools and found you only need about 6.

The Vertex site specifies the run out some distance past the end of the collet. In other words the error at the tip of a tool or piece of work that is sticking out of one is given directly at the length they specify. This is how it should be done. Others say anything from 1 to 15um run out but don't say where and I very much doubt if it is where Vertex specify it. More likely some where actually at the collet which doesn't say anything at all about the run out in use.

Plus of course UK sellers generally don't state anything at all. even ARC.

I've been here before with ER25 and finished up buying from the USA where they do generally state something even on ebay. I asked for some clarification in the correct terms and was told that a number had been checked and found to be much better than the standard tolerance so decided to trust him. These were spec'd as better than 0.0005". The seller had complaints from his customers in the past. Not with this batch.

I'm slowly coming to the same conclusion as John K. They aren't really suitable for lathe work, more bar work especially as the size goes up. My Boxford lathe collets are a bit limited on size so I keep wondering about obtaining larger sizes some how.

John

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Thanks, John

... I think I see what you are getting at, but; going by the table on that Vertex page it appears that 'L' is prescribed by DIN 6343 anyway.

Does anyone here have access to he DIN standards ?

MichaelG.

Edit: Just found this useful brochure.

Edited By Michael Gilligan on 15/10/2015 17:01:40

I use an ER40 collet chuck for round bar on my Boxford and have never had a problem, shown here threading studs

Wow! My ER25 collet holder lives on one of my lathes, and ER collet holders (ER 25 also) live on my milling machines. The ER40 on my largest lathe goes on quite a bit, but not right now, as I did something for a colleague and have not put the collet chuck back on.

Have purchased collets from Maritool in the USA, Regio-FX, some from Arc, and the "accurate" ones from CTC Tools. I don't mind spending money on something that will work well for the remainder of my life - crossing fingers it'll be at least 50 more productive years. (one lives in hope...)

I actually gave away my Clarkson endmill holder - had not been used for about 2 decades...

John.

As far as im concerned ER collets are the bees knees for anything up to 30mm Ø [34mm Ø if you go up to ER50]

Very accurate AND very repeatable. Wish I had bought an ER 40 lathe chuck long ago..

The Crawford catalogue is on line and gives their tolerance - also rather clear about intended use.

The trouble with variable sized collets as against spring types of a specific size is that they need bar in them right up to more or less the full length of the collet. Spring collets will generally work with a shorter length in them. They don't give the sized socket lengths in any info I have though so the comments might be a load of junk. I'd guess that the grip length of a spring collet will be about 1 1/2 to 2 times the diameter it's intended to hold. However - Measuring a 3C it's not far off 2 diameters, a bit less.. So for instance an ER 40 is comparable when it's holding 23mm. ER16 when it's holding 14mm. Spring collets such as 5C type are also reckoned to be happier gripping short than intended lengths. This is why this style of collet is sometimes referred to as work holding and the other bar holding - including Bernerd multi grip. Where I come from that would be called a bar chuck not a collet chuck.

Here endeth lesson on collet technology. It matters to me due to flexibility in use. The 5C type will still hold bar type work.

John

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There is NO collet system out there that does every job. Full stop.

Some are better than others for certain thing, like ER's can be both work holding and tool holding.

What you have to do is work out what you need to do, make a list and then start comparing and ticking boxes. The one with the most ticked boxes goes to the top of the list.

What works for me won't necessarily work for you and visa versa.

It's also territorial, the Yanks will use 5C and R8 and being the most common ones in their neck of the woods. Europe and the UK tend towards ER's and the 5C is virtually unheard of in OZ.

I have a virtually full set of metric and imperial full size 5C collets and the 4 most used ones are not in this lot but are emergency ones that have been drill and tapped M6 to M12 for holding one end of a double ended stud so the other end can be threaded and not mess the first thread up.

I dare say there will not be many on this board that wants to replicate what I have to do ?

John, For FULL specs on ER collets plus associated items may I suggest you talk with Dave Chambers at D&J Workholding on [email protected] and 01993 200119. They also supply a large range of styles of quality tooling arbours and collets . NOT CHEAP, but good . No connection with company other than as a satisfied customer. Hope this helps.

Trevor

I'm going through my ticks John. It very much looks like if I want to increase the size range of my work holding collets it will be spring collets and not ER. For tool holding yes ER.

Some of the decision comes from doing a fair amount of collet work but not at home. I don't purchase the wrong thing very often. I have a Bernerd multi size that will match ER40 but has the same problem so it's never been fitted. I bought it because some one who was giving up came along and offered it to me for the same price as Rotagrip offered him. I have also sorted the mounting info for it.

I don't really have any need for bigger work holding collets at the moment but I do need to sort out tool holding. As I have them I'm going to try ER25 with a rather large tool on the end.

Thanks for the thought on holding screw threads for studs John and maybe other thing. Makes me wonder if I can obtain some 3C emergency collets. Rare I suspect so probably stupidly expensive. I'd guess I could do the same with 3 morse blank ends but splitting them would be more work,

I'd beg to differ on 5C and similar types in the UK. Often they are collets designed specifically for the lathe they are on rather than a standard type like 5C but cost has tended to rule them out in the past. It's not so bad now but as I suspected I can buy a 5C collet chuck from the USA that has a sort of spec with it but not in the UK again - other than one seller and the spec was pretty bad. I'm getting pretty cheesed off about that. It's as bad as Ketan's motor power one. CTC is an alternative on ER.

As to the rest I thought it was worth mentioning as the reasons for the difference are real and not some ones imagination. What people choose to do on that score is up to them.

John

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